This invention relates to linear actuators and particularly to linear actuators which are employed in applications which require redundant actuating systems. The use in airplanes, space vehicles and propulsion systems and the like is exemplary. In such systems a linear actuator is used to drive a control such as a throttle linkage, a control surface such as a rudder or aileron or a movable nozzle assembly. In order to increase the reliability of such systems it is normal to employ redundant actuators such that in the event one actuator fails, control is not lost because a backup system is available. Position monitoring transducers and feedback networks are conventionally employed to monitor actuators, detect a failure and command the backup system to operate, as is known to the art. Even if a backup system is available, however, it is necessary to somehow disengage the failed actuator from the control to permit the operative actuator to function. For example, if the failure mode of the failed actuator was freezing of the output shaft in a particular position, the backup system could not operate the control until either the failed actuator was disengaged from the control or the actuator was "unfrozen". Although the prior art abounds in linear actuators of various types and configurations, no actuator exists in which a fail safe mechanism is provided to protect against either translational or rotational failure modes. Accordingly, it is an object of this invention to provide a fail safe electromechanical actuator.